Take a look at my interface with LM4970

#include "p24hxxxx.h"
#include "p24HJ64GP502.h"	
#include <stdio.h>
#include <stdlib.h>	
#include "i2c.h"
	 

#ifdef __PIC24HJ64GP502__
_FOSCSEL(FNOSC_FRC);	 // set oscillator mode for FRC ~ 8 Mhz
_FOSC(FCKSM_CSDCMD & OSCIOFNC_ON & POSCMD_NONE);	// use OSCIO pin for RA3
_FWDT(FWDTEN_OFF);	 // turn off watchdog
#elif defined(__dsPIC33FJ64MC802__)
_FOSCSEL(FNOSC_FRC);	
_FOSC(FCKSM_CSDCMD & OSCIOFNC_ON & POSCMD_NONE);
_FWDT(FWDTEN_OFF);	
#endif
#define LM4970_ADDR_0 0x7A // first 7 bits of address 0 (ADR = LOW)
#define LM4970_ADDR_1 0x7B // first 7 bits of address 1 (ADR = HIGH)
#define LM4970_MODE_NORM 0x00 // power up, normal I2C, no random
#define LM4970_MODE_RAND 0x04 // power up, normal I2C, random
#define LM4970_FREQ 0x50 // 6.3kHz High Pass / 15kHz PWM
#define LM4970_PATT_AUDIO 0x60 // pattern gen by audio input
#define LM4970_PATT_I2C 0x61 // pattern gen by I2C - all off
#define LM4970_CURR 0xAA // 1x current (21mA)on LED 1-3
#define LM4970_GAIN 0xEA // gain = 10dB / midband = medium
#define I2C_ON 0xFFFF
#define I2C_START_EN               0xFFFF



void i2c_init();
void i2c_send(int x, int y);

int main ()
{
OSCCON = 0x0000;    
OSCCONbits.COSC=1;                                     // FRC osc with PLL
OSCCONbits.NOSC=1;
OSCCONbits.IOLOCK=1;                                   //peripheral pins lock
CLKDIVbits.PLLPOST=1;                                    //N2=4
CLKDIVbits.PLLPRE=6;                                      //N1=8
CLKDIVbits.DOZE =1;                                        // doze 2
CLKDIVbits.DOZEN=1;
PLLFBDbits.PLLDIV=171;                                    // M=173
OSCTUN   = 0x0000;
RCONbits.SWDTEN     = 0;                         //Disable Watch Dog Timer
AD1PCFGL=0xFFFF;
PORTBbits.RB8=0;                               //clock on oin B8
PORTBbits.RB9=0;                                //data on pin B9 
                                  		

i2c_init(); // start I2C module

i2c_send(LM4970_ADDR_0,LM4970_MODE_NORM); // power up, normal I2C, no random

i2c_send(LM4970_ADDR_0,LM4970_FREQ); // 6.3kHz High Pass / 15kHz PWM

i2c_send(LM4970_ADDR_0,LM4970_PATT_AUDIO); // // pattern gen by audio input

i2c_send(LM4970_ADDR_0,LM4970_CURR); // 1x current (21mA)on LED 1-3

i2c_send(LM4970_ADDR_0,LM4970_GAIN); // gain = 10dB / midband = medium


I2C1CONbits.I2CEN = 0;  // stop I2C module



}

void i2c_init()
{
   I2C1BRG = 197;
   I2C1CONbits.I2CEN = 0;    // Disable I2C Mode
   I2C1CONbits.DISSLW = 1;    // Disable slew rate control
   IFS1bits.MI2C1IF = 0;    // Clear Interrupt
   I2C1CONbits.I2CEN = 1;    // Enable I2C Mode
   I2C1CONbits.RCEN = 0;
   I2C1STATbits.IWCOL = 0; // no collision
   I2C1STATbits.BCL = 0; // no collision on master bus
}

void i2c_send(int x, int y)
{
	I2C1CONbits.SEN = 1;  // start condition enable
	while(I2C1CONbits.SEN);

	I2C1TRN = x;             // place address into send register
	while(I2C1STATbits.TBF); 
    while(I2C1STATbits.TRSTAT);   
    while(I2C1STATbits.ACKSTAT); 

	I2C1TRN = y;               //place data into send register
	while(I2C1STATbits.TBF); 
    while(I2C1STATbits.TRSTAT);   
    while(I2C1STATbits.ACKSTAT);

	I2C1CONbits.PEN = 1;      // stop condition enable

	
	
}